阅读说明：本技术 耐疲劳的层状弹性体 (Fatigue resistant layered elastomers ) 是由 陈浩 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种耐疲劳的层状弹性体,以热可塑性聚酯弹性体为原料挤出长条线条体,卷曲粘结后形成一定厚度的层状物,相邻线条体接触部位彼此熔接,形成连续接合点或点接合点,其中连续接合点的占比在20%以上。连续接合点比率超过20%时,耐疲劳反复压缩硬度损失率低于23%,连续接合点所占比率越多,反复压缩耐久性越好,因而提高层状弹性体的连续接合点比率可以获得具有耐反复压缩性能的产品。(The invention discloses a fatigue-resistant layered elastomer, which takes thermoplastic polyester elastomer as raw material to extrude a long line body, forms a layered object with a certain thickness after curling and bonding, and the contact parts of adjacent line bodies are mutually welded to form a continuous joint or a point joint, wherein the occupation ratio of the continuous joint is more than 20%. When the ratio of continuous bonding points exceeds 20%, the fatigue repeated compression resistant hardness loss ratio is less than 23%, and the more the ratio of continuous bonding points is, the better the repeated compression durability is, so that increasing the ratio of continuous bonding points of the layered elastic body can yield a product having repeated compression resistant performance.)

1. A fatigue-resistant layered elastomer is prepared by taking a thermoplastic polyester elastomer as a raw material to extrude a strip line body, curling and bonding the strip line body to form a layered object with a certain thickness, and is characterized in that: the contact parts of adjacent lines are welded with each other to form a continuous joint (1) or a point joint (2), wherein the ratio of the continuous joint (1) is more than 20%.

2. The fatigue-resistant layered elastomer according to claim 1, wherein: the melt index of the thermoplastic polyester elastomer raw material is 15-25 g/10 min.

3. The fatigue-resistant layered elastomer according to claim 1, wherein: the melting point of the thermoplastic polyester elastomer raw material is below 180 ℃.

4. The fatigue-resistant layered elastomer according to claim 1, wherein: the continuous joint (1) is a welding part with the length being more than or equal to 5 mm.

5. The fatigue-resistant layered elastomer according to claim 1, wherein: the layered elastomer (3) is repeatedly compressed 8 ten thousand times at a compression force of 750N, and the hardness loss rate is less than 25%.

6. The fatigue-resistant layered elastomer according to claim 1, wherein: the 40% indentation hardness of the layered elastomer (3) is 100N-350N.

7. The fatigue-resistant layered elastomer according to claim 1, wherein: the thickness of the layered elastomer (3) is 20mm to 200mm, and the density is 30 kg/m to 100kg/m³。

8. The fatigue-resistant layered elastomer according to claim 1, wherein: the thread-shaped fiber of the layered elastomer (3) is a round solid thread, a special-shaped thread or a hollow thread.

9. The fatigue-resistant layered elastomer according to claim 1, wherein: the soft segment of the thermoplastic polyester elastomer raw material is polytetrahydrofuran ether.

10. The fatigue-resistant layered elastomer according to claim 1, wherein: the soft segment content of the polytetrahydrofuran ether in the raw material of the thermoplastic polyester elastomer is 70%, the melting point of the raw material is 171 ℃, and the melt index is 20g/10 min.

Technical Field

The invention relates to a layered elastomer with certain thickness formed by crimping long fiber yarns, wherein the long fiber yarns are made of thermoplastic polyester elastomer serving as a raw material, and the elastomer can be suitable for the fields of office chairs, sofas, beds and the like, in particular to a fatigue-resistant layered elastomer.

Background

The existing layered elastomer is usually prepared by a spinning mode, and specifically, the polyester elastomer in a molten state is extruded by a spinning plate at a certain speed and temperature, the extruded polyester elastomer falls into water for cooling, continuous filament bodies are bent into rings, contact parts are welded with each other, two sides of the continuous filament bodies are flattened, and finally the continuous filament bodies are cut into a three-dimensional reticular structure with required size. Since the existing layered elastic body is commonly used in a cushion, a mattress and the like, the repeated compression durability, i.e., fatigue resistance, is required to be considered.

Chinese patent CN109680412A discloses a net-like structure having a residual strain after repeated compression at 50% constant displacement of 15% or less and a hardness retention rate at 50% compression after repeated compression at 50% constant displacement of 85% or more. Paragraph 0048 of the patent describes that in order to obtain such a net-like structure, it is necessary to strengthen the junction strength between continuous linear bodies by firmly fusing the continuous linear bodies of the obtained net-like structure. The strength of the contact between the continuous linear bodies constituting the mesh structure is increased, thereby improving the repeated compression durability of the mesh structure. Paragraph 0049 and paragraph 0051 describe a method for obtaining a net-like structure with enhanced joint strength, which comprises: when spinning a polyester-based thermoplastic elastomer, a heat-insulating region is provided below a nozzle, the surface temperature of a web around the falling position of a continuous filament of a traction conveyor net is increased, the temperature of cooling water in a cooling tank around the falling position of the continuous filament is increased, and the like. The patent is to obtain a net-shaped structure with high joint strength by improving the manufacturing process of the product, so that the compression parameters of the product meet the expected values.

Chinese patent CN105683434B discloses a mesh structure with excellent compression durability, wherein the residual strain of 750N constant load repeated compression is 15% or less, the hardness retention ratio at 40% compression after 750N constant load repeated compression is 55% or more, and the hardness retention ratio at 65% compression after 750N constant load repeated compression is 70% or more. In order to obtain excellent compression durability, patent nos. 0056 and 0057 describe that the surface layer part and the inner layer part are provided with a structural difference (the fiber diameter of the surface layer part is 1.05 times or more the fiber diameter of the inner layer part) and the joint strength between the continuous linear bodies of the surface layer part is increased, and the joint strength of the surface layer part of the net-like structure is increased by increasing the joint area of the continuous linear bodies as compared with the inner layer part by providing the structural difference between the surface layer part and the inner layer part, and further, the joint breakage caused by the repeated compression treatment is suppressed, and the effect of surface dispersion of the load (750N) received by the repeated compression is continued in the surface layer part. The product is excellent in compression durability by imparting compressive strength to the surface layer of the product.

None of the above patents mentions the relationship between the random junction and the durability of the layered elastomer, the hardness loss rate of 750N layered elastomer product obtained in CN105683434B patent can only be maintained between 30% and 45% after repeated compression, and no further improvement in the durability of the layered elastomer product obtained based on the methods described in CN109680412A and CN105683434B patents can be obtained.

Disclosure of Invention

The present applicant has aimed at the above-mentioned disadvantages that a layered elastomer having more excellent durability cannot be obtained by the conventional production, and has provided a fatigue-resistant layered elastomer which is further improved in compression durability and service life by controlling the ratio of continuous joints.

The technical scheme and the beneficial effects adopted by the invention are as follows:

a fatigue-resistant laminated elastomer is prepared through extruding out long-strip lines from thermoplastic polyester elastomer, curling, adhering to form a laminated body, and welding the adjacent lines to form continuous or point jointer (20% or more). When the ratio of continuous bonding points exceeds 20%, the fatigue repeated compression resistant hardness loss ratio is less than 23%, and the more the ratio of continuous bonding points is, the better the repeated compression durability is, so that increasing the ratio of continuous bonding points of the layered elastic body can yield a product having repeated compression resistant performance.

As a further improvement of the above technical solution:

the melt index of the thermoplastic polyester elastomer raw material is 15-25 g/10 min. The invention finds that the melt index of the thermoplastic polyester elastomer raw material has an important relation with the ratio of continuous joints of the layered elastomer product, and when the melt index of the thermoplastic polyester elastomer raw material is 15-25 g/10min, the product with high ratio of the continuous joints and low fatigue-resistant repeated compression hardness loss rate can be obtained. When the melt index is more than 25g/10min, the continuous junction ratio of the product decreases and the compression durability is poor. This is considered to be because the larger the melt index is, the better the processing fluidity of the material is, the higher the speed of the continuous filament body flowing out from the spinneret is, the smaller the diameter of the continuous filament body is when the drawing rate is controlled to be constant, and the smaller the diameter is, the lower the probability of forming a continuous joint at the welded portion is, and therefore, the continuous joint ratio of the final product decreases.

When the melt index is less than 15g/10min, the continuous junction ratio of the product decreases and the compression durability is poor. It is considered that the smaller the melt index is, the lower the processing fluidity of the material is, and the lower the speed of the continuous filament body flowing out from the spinneret is, and the larger the diameter of the continuous filament body is when the drawing rate is controlled to be constant, but the flow speed of the continuous filament body is too slow and the temperature is lowered early in the lowering process, so that the number of fusion points formed after dropping into water decreases, and the probability of the fusion points forming continuous junctions also decreases, and therefore the ratio of the continuous junctions of the final product decreases.

The melting point of the thermoplastic polyester elastomer raw material is below 180 ℃. The invention finds that the melting point of the thermoplastic polyester elastomer raw material has an important relation with the ratio of continuous bonding points of the layered elastomer product, and when the melting index of the thermoplastic polyester elastomer raw material is below 180 ℃, the product with high ratio of continuous bonding points and low fatigue-resistant repeated compression hardness loss rate can be obtained. When the melting point of the polyester elastomer is more than 180 ℃, the continuous junction ratio of the product is decreased and the compression durability is poor. It is considered that the reason is that the melting point is too high, and the continuous filament bodies are not easily adhered to each other after extrusion in a molten state at 225 ℃, and the obtained product has a reduced number of welded portions and a reduced probability of forming continuous joints at the welded portions.

The continuous joint is a welding part with the length being more than or equal to 5 mm.

The hardness loss rate of the layered elastomer is less than 25 percent after the layered elastomer is repeatedly compressed for 8 ten thousand times under the compression force of 750N. Although the conventional products disclose that the fatigue resistance of the products can be improved by enhancing the joint strength or giving a poor structure to the surface layer part and the inner layer part, the hardness loss rate of the products manufactured by the conventional methods can only be maintained between 30 and 45% after 750N repeated compression, and a lower repeated compression hardness loss rate cannot be obtained, and the patent discloses that a layered elastic body with excellent repeated compression durability and hardness loss rate of less than 25% can be obtained by controlling the continuous joint rate to exceed 20%, and the layered elastic body is suitable for products with fatigue resistance requirements such as cushions and mattresses.

The 40% indentation hardness of the layered elastomer is 100N-350N.

The thickness of the layered elastomer is 20-200 mm, and the density is 30-100 kg/m 3.

The thread-shaped fiber of the layered elastomer is a round solid thread, a special-shaped thread or a hollow thread.

The soft segment of the thermoplastic polyester elastomer raw material is polytetrahydrofuran ether.

The soft segment content of the polytetrahydrofuran ether in the raw material of the thermoplastic polyester elastomer is 70%, the melting point of the raw material is 171 ℃, and the melt index is 20g/10 min. When the soft segment content of the polytetrahydrofuran ether in the raw material of the thermoplastic polyester elastomer is 70%, the melting point of the raw material is 171 ℃, and the melt index is 20g/10min, the continuous joint ratio is 31%, the fatigue-resistant repeated compression hardness loss rate is only 15%, and the fatigue resistance of the layered elastomer product is optimal.

Drawings

FIG. 1 is a schematic view of the structure of a layered elastomeric product.

In the figure: 1. a continuous junction; 2. a point-joining point; 3. a layered elastomer.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As a polyester-based thermoplastic elastomer, dimethyl terephthalate (DMT), 1, 4-butanediol (1, 4-BD), polytetramethylene glycol (PTMG), tetrabutyl titanate (TBT) catalyst, and a stabilizer Irganox 1010 were subjected to an esterification reaction at 230 ℃, and when the amount of methanol as a by-product was 98% or more of a theoretical value, they were polycondensed by heating to 245 ℃ and reducing the pressure to 100Pa in vacuum, and they were polymerized to a desired viscosity and pelletized, and finally a polyether ester block copolymer elastomer was produced, and the formulation of the resulting thermoplastic elastomer resin material was shown in table 1, in which the melt index was controlled by controlling the production condition parameters such as polymerization time.

Table 1:

the specific test method is as follows:

1. thickness: randomly selecting 3 samples, measuring the thickness of the product by using a thickness meter, and calculating an average value.

2. Density: and putting the product into an oven, setting the oven at 80 ℃ for 3hr, measuring the length, the width and the height of the product after ensuring that the moisture is removed to calculate the volume, weighing the product by a three-position precision balance accurate to decimal point, and dividing the weight by the volume to calculate the density.

3. Wire diameter: randomly extracting 5 fibers from the three-dimensional net structure, measuring the diameter of the 3 positions by using a 20-time optical microscope and a scale, calculating the average diameter of each fiber, and calculating the average value of the 5 fibers.

4. 40% indentation hardness test: under the constant temperature of 23 ℃, the product is placed between an upper pressure plate and a lower pressure plate, the product is compressed to the strain of 40% at the test speed of 100mm/min, the upper pressure plate compresses the product downwards, a load cell at the upper end senses the pressure, the pressure is converted into a voltage signal and is transmitted to a display for analysis, the pressure value is displayed on a screen at the same time, and the average value is obtained after three tests.

5. Fatigue-resistant repeated compression hardness loss rate: and (3) putting the product on a lower platform of a repeated compression tester at a constant temperature of 23 ℃, repeatedly compressing the product at a compression force of 750N and a frequency of 70 times per minute, and evaluating the performance of the product after compressing for 8 ten thousand times. Fatigue-resistant repeated compression hardness loss rate = (40% indentation hardness before product test-40% indentation hardness after product test)/40% indentation hardness before product test 100%, and 3 samples were measured and averaged.

6. Bonding point: a sample having a size of 5cm × 5cm was weighed with a precision balance until the weight was calculated to the decimal point first, and as shown in fig. 1, the intersection defining the length of the welding portion between the umbilical member and the umbilical member of the layered elastic body 3, which is less than 5mm, was referred to as a point joint 2, and the intersection defining the length of the welding portion between the umbilical member and the umbilical member, which is greater than or equal to 5mm, was referred to as a continuous joint 1. The counter carefully peeled the intersection of the umbilical member and the umbilical member, carefully observed and counted the number of the spot-join points 2 and the continuous join points 1, and divided the number of the obtained join points by the sample weight to obtain the number of spot-join points per unit volume and the number of continuous join points (unit: pieces/g). Continuous joint ratio = number of continuous joints/(number of continuous joints + number of point joints).