TWI823337B - Modified polyurethane carrier substrate - Google Patents

Abstract

A modified polyurethane carrier substrate is provided. The modified polyurethane carrier substrate is formed from a modified polyurethane. The modified polyurethane includes a soft segment and a hard segment. The soft segment is formed from polyol. The hard segment is formed from diisocyanate and a chain extender. The chain extender is dianhydride. A common logarithm of a ratio of a storage modulus of the modified polyurethane membrane at -30°C to a storage modulus of the modified polyurethane membrane at 150°C ranges from 0.40 to 1.30.

Description

Modified polyurethane load-bearing substrate

The present invention relates to a modified polyurethane bearing base material, in particular to a modified polyurethane bearing base material with good heat resistance.

After the concept of the metaverse emerged, wearable devices related to augmented reality (AR) and virtual reality (VR) have gradually received more attention.

In the research and development process of wearable devices, how to improve the functionality and practicality of wearable devices has become the research direction of this business. In order to improve the functionality and practicality of wearable devices, the demand for the characteristics of flexible printed circuit boards (FPCs) is gradually increasing in the market. In addition to hoping that the flexible printed circuit board has good elastic strength for flexing, it also needs to have good heat resistance to meet the manufacturing process requirements.

Most of the smart fabrics and interactive textiles (SFIT) currently on the market (such as heart rate sensing clothing) use polyurethane as the material for flexible printed circuit boards because polyurethane is soft, wear-resistant, impact-resistant and elastic. Good features. However, polyurethane has poor heat resistance and cannot withstand higher processing temperatures. Therefore, how to provide polyurethane materials with good heat resistance has become one of the important issues to be solved in this business.

The technical problem to be solved by the present invention is to provide a modified polyurethane bearing base material in view of the shortcomings of the existing technology.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a modified polyurethane bearing base material. The modified polyurethane bearing base material is formed of a modified polyurethane. Modified polyurethane includes a soft segment and a hard segment. The soft segment is made of polyol, and the hard segment is made of diisocyanate and a chain extender. The chain extender is a dianhydride. The commonly used logarithm of the ratio of the storage modulus of modified polyurethane at -30°C to the storage modulus at 150°C is 0.40 to 1.30.

In some embodiments, the chain extender is selected from the group consisting of: pyromellitic dianhydride (PMDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (1, 2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA), diphenyltetracarboxylic anhydride (BPDA), 3,3',4,4'-benzylphenol tetracarboxylic anhydride (3, 3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4.4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-oxydiphthalic anhydride (6FDA) Dicarboxylic anhydride (4,4'-oxydiphthalic anhydride, ODPA), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 4,4'-( 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride), BPADA) and its mixtures.

In some embodiments, the total weight of the modified polyurethane carrier substrate is 100 weight percent, and the content of the chain extender is 10 to 35 weight percent.

In some embodiments, the total weight of the modified polyurethane is 100 weight percent, and the content of the hard segment is 20 to 70 weight percent. Preferably, the content of hard segments is 30 to 50 weight percent.

In some embodiments, the hard segment includes a crankshaft structure. The crankshaft structure changes the molecular chain direction of the modified polyurethane. The crankshaft structure is formed of diisocyanate.

In some embodiments, the diisocyanate forming the crankshaft structure is selected from the group consisting of: 1,3-bis(isocyanatomethyl)cyclohexane, H6XDI), isophorone diisocyanate (IPDI), 1,3-bis(2-isocyanato-2-propyl) )benzene, TMXDI), m-xylyene diisocyanate (m-XDI), 2,4'-diphenylmethane diisocyanate (2,4'-methylenebis(phenyl isocyanate), 2,4' -MDI), 2,2'-diphenylmethane diisocyanate (2,2'-methylenebis(phenyl isocyanate), 2,2'-MDI) and combinations thereof.

In some embodiments, the total weight of the modified polyurethane is 100 weight percent, and the content of the crankshaft structure is 10 to 25 weight percent.

In some embodiments, the hard segment further includes a linear structure, and the diisocyanate forming the linear structure is selected from the group consisting of: 4,4'-diphenylmethane diisocyanate (4,4 '-methylenebis (phenyl isocyanate), 4,4'-MDI), 4,4'-diisocyanato-methylenedicyclohexane (H12MDI), hexamethylene diisocyanate (hexamethylene diisocyanate, HDI) and compositions thereof.

In some embodiments, the mass ratio of the diisocyanate forming the crankshaft structure and the diisocyanate forming the linear structure is 1:0.8 to 1.2.

In order to solve the above technical problems, another technical solution adopted by the present invention is to provide a modified polyurethane bearing base material. The modified polyurethane load-bearing substrate is formed of a modified polyurethane, and the modified polyurethane includes a soft segment and a hard segment. The hard segment contains a crankshaft structure to change the molecular chain direction of the modified polyurethane. The storage modulus of the modified polyurethane at -30°C is the same as that at -30°C. The common logarithm of the ratio of storage modulus at 150°C is 0.40 to 1.30.

One of the beneficial effects of the present invention is that the modified polyurethane load-bearing substrate provided by the present invention can be used by "the chain extender is a dianhydride" and "the storage modulus of the modified polyurethane at -30°C is the same as that at 150°C. The commonly used logarithm of the storage modulus ratio is 0.40 to 1.30", which makes the modified polyurethane load-bearing substrate have good heat resistance.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description of the present invention. However, the description provided is not intended to limit the present invention.

The following is a specific example to illustrate the implementation of the "modified polyurethane bearing substrate" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of the present invention. In addition, the term "or" used in this article shall include any one or combination of more of the associated listed items depending on the actual situation.

The invention provides a modified polyurethane bearing base material, which can be used to bear integrated circuits so as to be applied to smart textiles. The modified polyurethane carrier substrate has good elastic strength and heat resistance and can be used to manufacture flexible printed circuit boards. The thickness of the modified polyurethane bearing base material of the present invention is not limited. Specifically, the modified polyurethane bearing base material can be a film-like base material or a plate-like base material that is well known in the technical field.

The modified polyurethane bearing base material of the present invention is made of modified polyurethane. Modified polyurethane is composed of a soft segment and a hard segment arranged in a staggered manner. The present invention adjusts the hard segment The structure improves the elastic strength and heat resistance of modified polyurethane. Moreover, the modified polyurethane of the present invention can have good elastic strength regardless of high temperature or low temperature environment.

It is worth noting that in the prior art, the effect of adjusting the elastic strength of modified polyurethane is mostly achieved by changing the structure of the soft segment or by changing the content ratio of the soft segment to the hard segment. In contrast, the present invention achieves the effect of adjusting the elastic strength of modified polyurethane by changing the structure of the hard segment.

In the specification, the present invention evaluates the elastic strength of modified polyurethane through the measurement of storage modulus (E'). In addition, the present invention measures the storage modulus of modified polyurethane at low temperature (-30°C) and high temperature (150°C) respectively, and takes the common logarithm (log10) (log(E'() as the ratio after dividing the storage modulus) -30℃)/E'(150℃))), as a reference for evaluating the difference in elastic strength of materials at low and high temperatures.

In the present invention, the common logarithm of the ratio of the storage modulus of the modified polyurethane at -30°C to the storage modulus at 150°C is 0.40 to 1.30. Preferably, the common logarithm of the ratio of the storage modulus of the modified polyurethane at -30°C to the storage modulus at 150°C is 0.7 to 1.2. The specific measurement methods and results will be described later.

In the present invention, the contents of soft segment and hard segment can be adjusted according to the characteristic requirements. In some embodiments, the total weight of the modified polyurethane is 100 weight percent, and the content of the hard segment is 20 to 70 weight percent. However, the present invention is not limited to this.

In the modified polyurethane of the present invention, the hard segment is formed of diisocyanate and a chain extender. The soft segments are formed from polyols.

[Chain extender]

The chain extender is a dianhydride. The use of the chain extender can improve the heat resistance and physical properties of modified polyurethane. Even at higher temperatures, modified polyurethane still has high thermal creep recovery properties. In this way, the modified polyurethane of the present invention can withstand higher loading operating temperature and can meet the process requirements of flexible printed circuit boards.

In an exemplary embodiment, the number average molecular weight of the chain extender is 150 g/mol to 550 g/mol. However, the present invention is not limited to this.

In an exemplary embodiment, the chain extender is a dianhydride. Preferably, the chain extender can be pyromellitic anhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, diphenyltetracarboxylic anhydride, 3,3',4,4'-benzylphenol Tetracarboxylic anhydride, 4,4'-(hexafluoroisopropylene) diteric anhydride, 4,4'-oxydiphthalic anhydride, 3,4,9,10-perylene tetracarboxylic dianhydride, 4, 4'-(4,4'-isopropyldiphenoxy)bis(phthalic anhydride) or mixtures thereof. More preferably, the chain extender is pyromellitic anhydride. However, the present invention is not limited to this.

In an exemplary embodiment, the total weight of the modified polyurethane is 100 weight percent, and the content of the chain extender is 10 to 35 weight percent. However, the present invention is not limited to this.

[Diisocyanate]

The hard segments may be formed from one or more diisocyanates. Among them, part of the diisocyanate will form a crankshaft structure after the synthesis reaction, and the other part of the diisocyanate will form a straight chain structure after the synthesis reaction.

In some embodiments, the diisocyanates may all form a crankshaft structure. In some embodiments, the diisocyanates may all form a linear structure. In some embodiments, a portion of the diisocyanate forms a crankshaft structure, and a portion of the diisocyanate forms a linear structure.

The existence of the crankshaft structure changes the molecular chain direction of the modified polyurethane, so that the modified polyurethane of the present invention has good elastic strength. In a preferred embodiment, the hard segment in the modified polyurethane includes a crankshaft structure.

The main structure of the crankshaft structure may be composed of cyclohexane or one or more benzene rings. The crankshaft structure has two functional groups, and the two functional groups are connected to cyclohexane or one or more benzene rings. In order to achieve the effect of changing the direction of the modified polyurethane molecular chain, the two functional groups will not be placed at opposite positions on the main structure.

Specifically, when the main structure of the crankshaft structure is a benzene ring, the two functional groups will not be placed at the para position of the benzene ring. When the main structure of the crankshaft structure contains two benzene rings (for example, diphenylmethane), the two functional groups will not be respectively located at the 4th position of the two benzene rings. Similarly, when the main structure of the crankshaft structure is cyclohexane, the two functional groups will not be placed at opposite positions on the cyclohexane.

In an exemplary embodiment, when the main structure of the crankshaft structure is a benzene ring, two functional groups may be disposed at the meta position of the benzene ring. When the main structure of the crankshaft structure contains two benzene rings (for example: diphenylmethane), the two functional groups can be respectively arranged at position 2 of one benzene ring and position 4 of the other benzene ring, or both The functional groups are respectively placed at position 2 of the two benzene rings.

Preferably, the crankshaft structure is formed of aliphatic isocyanate, and the two functional groups of the crankshaft structure are isocyanate groups. For example, when the main structure of the crankshaft structure is cyclohexane, the diisocyanate forming the crankshaft structure may be 1,3-di(isocyanatomethyl)cyclohexane or isophorone diisocyanate.

Preferably, the crankshaft structure is formed of aromatic isocyanate, and the two functional groups of the crankshaft structure are isocyanate groups. For example, when the main structure of the crankshaft structure is a benzene ring, the diisocyanate forming the crankshaft structure may be 1,3-bis(2-isocyanato-2-propyl)benzene or isocyanate. When the main structure of the crankshaft structure contains two benzene rings (for example: diphenylmethane), the diisocyanate forming the crankshaft structure can be 2,4'-diphenylmethane diisocyanate or 2,2'-diphenylmethane diisocyanate. Isocyanates. In some embodiments, m-xylylenedimethyl isocyanate and 2,4'-diphenylmethane diisocyanate can also be used simultaneously as monomers to form the crankshaft structure.

In an exemplary embodiment, assuming that the total weight of the modified polyurethane is 100 weight percent, the content of the crankshaft structure is 10 to 25 weight percent. More preferably, the content of the crankshaft structure can be 12 or 23 weight percent. However, the present invention is not limited to this.

The number average molecular weight of the diisocyanate forming the crankshaft structure may be from 150 g/mol to 300 g/mol. On the other hand, the number average molecular weight of the diisocyanate forming a linear structure may be from 100 g/mol to 400 g/mol. However, the present invention is not limited to this.

For example, the diisocyanate forming a linear structure may be 4,4'-diphenylmethane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, hexamethylene diisocyanate or a combination thereof. Preferably, the diisocyanate forming a linear structure is 4,4'-diphenylmethane diisocyanate. However, the present invention is not limited to this.

It is worth mentioning that the biggest difference between the diisocyanate forming a crankshaft structure and the diisocyanate forming a linear structure is that they have different structures. In other words, the diisocyanate forming the crankshaft structure and the diisocyanate forming the linear structure may be isomers.

When the diisocyanate forming a crankshaft structure interacts with the diisocyanate forming a linear structure, When it is an isomer, modified polyurethane can have a lower glass transition temperature and better elasticity and flexibility. For example: the crankshaft structure is formed by 2,4'-diphenylmethane diisocyanate, and the linear structure is formed by 4,4'-diphenylmethane diisocyanate.

In an exemplary embodiment, the mass ratio of the diisocyanate forming the crankshaft structure and the diisocyanate forming the linear structure is 1:0.8 to 1.2. However, the present invention is not limited to this.

[polyol]

The addition of polypolyol can reduce the glass transition temperature of modified polyurethane, thereby improving the elastic strength of modified polyurethane. In some embodiments, the polypolyol may be a polyester polyol (e.g., polydibutyl adipate or polycaprolactone), a polycarbonate polyol, or a polyether polyol (e.g., poly(dibutyl adipate) or polycaprolactone). tetramethylene ether glycol). However, the present invention is not limited to this.

In some embodiments, the polypolyol has a number average molecular weight of 400 g/mol to 4000 g/mol. However, the present invention is not limited to this.

The modified polyurethane of the present invention can be represented by formula (I):

In formula (I), R ₁ may be formed from the following diisocyanates: 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, 1,3-bis(2- Isocyanato-2-propyl)benzene, isocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl methylmethane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, hexamethylene diisocyanate and combinations thereof. R ₂ may be formed from a polypolyol having a number average molecular weight of 50 g/mol to 4000 g/mol. _R3 may be cyclohexane, benzene, biphenyl, benzophenone, diphenylpropane, diphenyl ether, tetracarboxylic acid or phenolmethane with a tetravalent bond. n and m are each independently an integer between 1 and 100.

More specifically, the modified polyurethane of the present invention can be represented by formula (II). In formula (II), n and m are each independently an integer between 1 and 100.

是選自於由下列所構成的群組：

In formula (II),

is selected from the group consisting of:

Specific examples are listed below to illustrate the synthesis method of modified polyurethane and the formation of the modified polyurethane bearing substrate.

[Example 1]

16.8 grams of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) (crankshaft structure), 16.8 grams of 4,4'-diphenylmethane diisocyanate (4,4'-MDI) ( Linear chain structure) and 100 grams of polycaprolactone (PCL) are stirred and mixed at a temperature of 80°C and a rotation speed of 300 rpm to form a polyurethane prepolymer. In Example 1, the theoretical bondable isocyanate group (NCO) in the polyurethane prepolymer is 5.20%.

17.2 grams of pyromellitic anhydride (PMDA) (chain extender) was dissolved in N-methylpyrrolidone (NMP) and added to the polyurethane prepolymer at 60°C. Then, stir and mix at a temperature of 60° C. and a rotation speed of 300 rpm to obtain a modified polyurethane solution. The solid content of the modified polyurethane solution is 45 wt%. After the modified polyurethane solution is centrifuged, dried (drying at a temperature of 70°C for 4 hours) and matured (drying at a temperature of 180°C for 2 hours), the modified polyurethane of the present invention can be obtained, and can be further made into modified polyurethane load-bearing substrate.

In Example 1, the content of the chain extender (pyromellitic anhydride) in the modified polyurethane was 11.4wt%. The content of the crankshaft structure in the modified polyurethane is 11.1wt%.

[Examples 2 to 4]

The synthesis method of the modified polyurethane carrier substrate in Examples 2 to 4 is similar to that in Example 1, and the difference lies in that the added amounts of diisocyanate and chain extender are different. Examples 1 to 4 can be used to compare the effects of different hard segment contents on the properties of modified polyurethane. Please refer to Table 1 for the content of theoretically bondable isocyanate groups (NCO) and chain extenders in the polyurethane prepolymer and the content of the crankshaft structure in the modified polyurethane.

In Example 2, the added amount of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) was 23.1 grams, and the amount of 4,4'-diphenylmethane diisocyanate (4,4'-MDI ) was added in an amount of 23.1 grams, and pyromellitic anhydride (PMDA) was added in an amount of 27.7 grams.

In Example 3, the added amount of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) was 31.7 grams, and the amount of 4,4'-diphenylmethane diisocyanate (4,4'-MDI ) is 31.7 grams, and pyromellitic anhydride (PMDA) is added in an amount of 42.1 grams.

In Example 4, the added amount of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) was 98.9 grams, and the amount of 4,4'-diphenylmethane diisocyanate (4,4'-MDI ) is 98.9 grams, and pyromellitic anhydride (PMDA) is added in an amount of 154.5 grams.

[Examples 5 to 8]

The synthesis method of the modified polyurethane in Examples 5 to 8 is similar to that in Example 1. The difference lies in that the addition amounts of diisocyanate and chain extender are different, and different diisocyanates are used. Examples 5 to 8 can be used to compare the effects of different hard segment structures on the properties of modified polyurethane. Please refer to Table 1 for the type of diisocyanate, the theoretically bondable isocyanate group (NCO) in the polyurethane prepolymer, the content of the chain extender, and the content of the crankshaft structure in the modified polyurethane.

In Example 5, the diisocyanate is 4,4'-diphenylmethane diisocyanate (4,4'-MDI) (linear structure). The added amount of 4,4'-diphenylmethane diisocyanate (4,4'-MDI) was 46.5 grams, and the added amount of pyromellitic anhydride (PMDA) was 27.6 grams.

In Example 6, the diisocyanate is 4,4'-diisocyanato-methylenedicyclohexane (H12MDI) (linear structure). The added amount of 4,4'-diisocyanate dicyclohexylmethane is 47.3 grams, and the added amount of pyromellitic anhydride (PMDA) is 27.3 grams.

In Example 7, the diisocyanate is hexamethylene diisocyanate (HDI) (linear structure). The added amount of hexamethylene diisocyanate is 35.0 grams, and the added amount of pyromellitic anhydride (PMDA) is 32.4 grams.

In Example 8, the diisocyanate is m-xylylene diisocyanate (m-XDI) (crankshaft structure). The added amount of m-xylylene isocyanate is 37.8 grams, and the added amount of pyromellitic anhydride (PMDA) is 31.1 grams.

[Comparative example 1]

29.2 grams of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) (crankshaft structure), 29.2 grams of 4,4'-diphenylmethane diisocyanate (4,4'-MDI) ( Linear chain structure) and 100 grams of polycaprolactone (PCL) are stirred and mixed at a temperature of 80°C and a rotation speed of 300 rpm to form a polyurethane prepolymer. In Comparative Example 1, the theoretically bondable isocyanate groups (NCO) in the polyurethane prepolymer were 9.58%.

Add 15.6 grams of 1,4-butanediol (1,4-BDO) to the polyurethane prepolymer at 70°C. Then stir and mix to obtain a polyurethane colloid, the solid content of the polyurethane colloid is 100wt%. After the polyurethane colloid is centrifuged, dried (dried at 100°C for 2 hours) and matured (dried at 100°C for 15 hours), polyurethane can be obtained, and a polyurethane bearing substrate can be prepared.

In Comparative Example 1, the content of the chain extender (1,4-butanediol) in the polyurethane was 8.97wt%. The content of the crankshaft structure in polyurethane is 16.8wt%.

[Feature test]

In order to conveniently compare the differences between the modified polyurethane of the present invention and existing polyurethanes, the modified polyurethane load-bearing substrates of the above-mentioned Examples 1 to 3, 5 to 8 and the polyurethane load-bearing substrate of Comparative Example 1 were tested for their characteristics. Listed in Table 2.

In Table 2, the Young’s modulus, tensile strength and elongation at break of the modified polyurethane load-bearing substrate are measured according to the standard test method of ASTM D638 (type V). Toughness is calculated by calculating the area under the stress-strain curve.

In Table 2, the glass transition temperature of the modified polyurethane support substrate, the storage modulus at -30°C (E'(-30°C)), and the storage modulus at 150°C (E'(150°C) ), measured using a dynamic mechanical analyzer (Brand: TECHMAX, Model: TA7000). In addition, the ratio after dividing the storage modulus is taken as the common logarithm (log10) (log(E’(-30℃)/E’(150℃))), which is used as a reference to evaluate the difference in elastic strength of materials at low and high temperatures.

In Table 2, the thermal expansion coefficient and thermal creep recovery of modified polyurethane are measured using a thermomechanical analyzer (Brand: TA, Model: TMA450). The measurement of thermal creep recovery is to apply an external force of 0.05N for 10 minutes at a temperature of 150°C, and then calculate the recovery rate after relaxing the external force for 20 minutes.

In Table 2, the 5wt% thermogravimetric loss and ash content of modified polyurethane are measured using a thermogravimetric analyzer (Brand: HITACHI, Model: STA7200).

In Table 2, the 25% permanent deformation rate of the modified polyurethane load-bearing substrate is measured according to the standard test method of ISO 2285.

In Table 2, the moisture absorption rate of the modified polyurethane load-bearing substrate is measured according to the standard test method of ASTM D570.

It can be seen from the results in Table 2 that compared with existing polyurethane films, the modified polyurethane carrier substrate of the present invention has better physical properties (such as Young's coefficient and toughness).

According to the contents of Examples 1 to 3, when the content of the chain extender (pyromellitic anhydride) increases, the Young's modulus of the modified polyurethane bearing substrate will increase accordingly. In order to balance the elastic strength and mechanical strength of the modified polyurethane bearing base material, the total weight of the modified polyurethane bearing base material is 100 weight percent, and the content of the chain extender is preferably 10 to 35 weight percent. Preferably, the content of the chain extender is 10 to 25 weight percent. More preferably, the content of the chain extender is 12 to 22 weight percent.

In the present invention, the Young's modulus of the modified polyurethane bearing base material is 20 MPa to 400 MPa. Preferably, the Young's modulus of the modified polyurethane bearing base material is 25 MPa to 350 MPa. The tensile strength of the modified polyurethane bearing base material is 10MPa to 65MPa. Preferably, the tensile strength of the modified polyurethane bearing base material is 14MPa to 63MPa. The toughness of the modified polyurethane bearing base material is 4.5GJ/m ³ to 18GJ/m ³ . Preferably, the toughness of the modified polyurethane bearing base material is 5GJ/m ³ to 15GJ/m ³ . The elongation rate of the modified polyurethane load-bearing base material is 300% to 700%. Preferably, the elongation rate of the modified polyurethane load-bearing base material is 350% to 680%.

It can be seen from the results in Table 2 that compared with the existing polyurethane film, the modified polyurethane carrier substrate of the present invention has better heat resistance (such as thermal expansion coefficient, thermal creep recovery).

According to the content of Examples 1 to 3, when the content of the chain extender (pyromellitic anhydride) increases, the heat resistance of the modified polyurethane bearing substrate will increase. However, when the content of the chain extender is too high (Example 4, the hard segment content is greater than 75 wt%), brittle cracking will occur and a continuous film cannot be formed.

In the present invention, the thermal expansion coefficient of the modified polyurethane bearing base material is 1.5 μm/°C to 4.0 μm/°C. Preferably, the thermal expansion coefficient of the modified polyurethane bearing base material is 1.8 μm/°C to 3.9 μm/°C. The thermal creep recovery of the modified polyurethane bearing substrate at 150°C is 50% to 80%. Preferably, the thermal creep recovery of the modified polyurethane bearing substrate at 150°C is 60% to 75%. The glass transition temperature of the modified polyurethane load-bearing substrate is -35°C to -60°C. The storage modulus of the modified polyurethane bearing base material at -30°C is 2.0×10 ⁷ to 5.0×10 ⁹ . Preferably, the storage modulus of the modified polyurethane bearing base material at -30°C is 3.0×10 ⁷ to 2.0×10 ⁹ . The storage modulus of the modified polyurethane bearing base material at 150°C is 5.5×10 ⁶ to 3×10 ⁸ . Preferably, the storage modulus of the modified polyurethane bearing base material at 150°C is 5.7×10 ⁶ to 2.0 ×10 ⁸ . The ratio of the common logarithm of the storage modulus of the modified polyurethane at -30°C to the common logarithm of the storage modulus at 150°C is 0.40 to 1.30. Preferably, the storage modulus of the modified polyurethane at -30°C The ratio of the common logarithm of to the common logarithm of the storage modulus at 150°C is 0.7 to 1.2.

Compared with existing polyurethane films, the modified polyurethane carrier base material of the present invention has a lower moisture absorption rate, so it is suitable for use in manufacturing flexible printed circuit boards. Specifically, the moisture absorption rate of the modified polyurethane load-bearing substrate is less than 1.12%. Preferably, the moisture absorption rate of the modified polyurethane load-bearing substrate is less than 0.8%.

[Beneficial effects of the embodiment]

One of the beneficial effects of the present invention is that the modified polyurethane load-bearing substrate provided by the present invention can be measured by the common logarithm of "the chain extender is a dianhydride" and "the storage modulus of the modified polyurethane at -30°C and The technical solution in which the ratio of the common logarithm of the storage modulus at 150°C is 0.40 to 1.30" enables the modified polyurethane load-bearing substrate to have good heat resistance.

Furthermore, the present invention achieves the effect of improving the heat resistance of the modified polyurethane bearing base material by selecting a specific chain extender and controlling its content. In addition, by making the hard segment include a crankshaft structure (adjusting the structure of the hard segment), the elastic strength of the modified polyurethane load-bearing base material is improved.

The contents disclosed above are only preferred and feasible embodiments of the present invention, and do not limit the patentable scope of the present invention. Therefore, all equivalent technical changes made using the contents of the description of the present invention are included in the patentable scope of the present invention. .

Claims (9)

A modified polyurethane load-bearing substrate, which is formed of a modified polyurethane, wherein the modified polyurethane includes a soft segment and a hard segment, the soft segment is formed of polypolyol, and the The hard segment is formed of diisocyanate and a chain extender. The chain extender is a dianhydride. The ratio of the storage modulus of the modified polyurethane at -30°C to the storage modulus at 150°C is commonly used. The logarithm is 0.40 to 1.30; wherein the total weight of the modified polyurethane is 100 weight percent, and the content of the chain extender is 10 to 35 weight percent. The modified polyurethane bearing base material as claimed in claim 1, wherein the chain extender is selected from the group consisting of: pyromellitic anhydride, 1,2,4,5-cyclohexanetetrakis Formic dianhydride, diphenyltetracarboxylic anhydride, 3,3',4,4'-benzylphenoltetracarboxylic anhydride, 4,4'-(hexafluoroisopropylene)dioic anhydride, 4,4'-oxygen Bisphthalic anhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-(4,4'-isopropyldiphenoxy)bis(phthalic anhydride) and its mixture. The modified polyurethane bearing substrate according to claim 1, wherein the content of the hard segment is 30 to 50 weight percent based on the total weight of the modified polyurethane being 100 weight percent. The modified polyurethane bearing base material according to claim 1, wherein the hard segment includes a crankshaft structure that changes the molecular chain direction of the modified polyurethane, and the crankshaft structure is composed of the Formed from diisocyanates. The modified polyurethane bearing substrate according to claim 4, wherein the diisocyanate forming the crankshaft structure is selected from the group consisting of: 1,3-bis(methyl isocyanate) Cyclohexane, isophorone diisocyanate, 1,3-bis(2-isocyanato-2-propyl)benzene, isocyanate, 2,4'-diphenylmethane diisocyanate , 2,2'-diphenylmethane diisocyanate and compositions thereof. The modified polyurethane bearing base material as described in claim 4, wherein the modified The total weight of polyurethane is 100 weight percent, and the content of the crankshaft structure is 10 to 25 weight percent. The modified polyurethane bearing base material according to claim 4, wherein the hard segment further includes a straight chain structure, and the diisocyanate forming the straight chain structure is selected from the group consisting of : 4,4'-diphenylmethane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, hexamethylene diisocyanate and their combinations. The modified polyurethane bearing base material according to claim 7, wherein the mass ratio of the diisocyanate forming the crankshaft structure and the diisocyanate forming the linear structure is 1:0.8 to 1.2. A modified polyurethane load-bearing substrate, which is formed from a modified polyurethane, wherein the modified polyurethane includes a soft segment and a hard segment, and the hard segment is made of diisocyanate and a chain extender Formed, the chain extender is a dianhydride, and the hard segment contains a crankshaft structure to change the molecular chain direction of the modified polyurethane. The storage modulus of the modified polyurethane at -30°C is the same as that at -30°C. The common logarithm of the storage modulus ratio at 150° C. is 0.40 to 1.30; wherein the total weight of the modified polyurethane is 100 weight percent, and the content of the chain extender is 10 to 35 weight percent.