CN103849348B - A kind of composition of polyester hot-melt adhesive and preparation method thereof - Google Patents

Abstract

The invention relates to a polyester hot melt adhesive composition and a preparation method thereof. It contains: a) polyester diol, which is the polycondensation reaction product of dibasic carboxylic acid component and _C2-6 dibasic alcohol component, said dibasic carboxylic acid component contains terephthalic acid and non- The essential isophthalic acid and C _4-12 aliphatic dicarboxylic acid units with a weight average molecular weight of 10,000-100,000, and b) C _16-20 fatty acid strontium. The polyester hot-melt adhesive composition of the invention has good fluidity and melting stability.

Description

A kind of polyester hot melt adhesive composition and preparation method thereof

technical field

The invention relates to a polyester hot-melt adhesive composition and a preparation method thereof, in particular to a polyester hot-melt adhesive composition with high fluidity and melting stability and a preparation method thereof.

Background technique

Polyester hot melt adhesive is an environmentally friendly and pollution-free green adhesive, which is obtained by esterification (or transesterification) and polycondensation of one or more dibasic acids (or esters) and diols. The coating method of polyester hot melt adhesive is generally melt coating, so the fluidity of the glue at a certain temperature has a great influence on the quality and efficiency of coating. If the fluidity of the glue is good, the coating or molding processing temperature is low, the energy consumption is low, and the coating speed and quality are good; the fluidity of the glue is poor, and the permeability and spreadability during coating are also poor, which not only increases the amount of glue , also affects the bonding performance. Due to the high-temperature melt coating, polyester hot-melt adhesives are also required to have good melt stability.

The main measure in the prior art to improve the fluidity of polyester is to add flow modifiers for screw blending. For polyester production enterprises, screw blending increases the process and cost, and affects production efficiency.

Therefore, there is an urgent need in the art for a polyester hot-melt adhesive with good fluidity and melt stability.

Contents of the invention

The main purpose of the present invention is to provide a polyester hot-melt adhesive composition with good fluidity and stable melting and a preparation method thereof.

A kind of high fluidity polyester hot-melt adhesive composition of the present invention comprises:

a) polyester diol, which is the polycondensation reaction product of dibasic carboxylic acid component and _C2-6 dibasic alcohol component, and described dibasic carboxylic acid component comprises terephthalic acid and optional C _4-12 Aliphatic dicarboxylic acids and isophthalic acids, which have a weight-average molecular weight of 10,000 to 100,000, and

b) Strontium C _16-20 fatty acid.

The present invention also provides a kind of preparation method of the polyester hot-melt adhesive composition of high fluidity, and it comprises the steps:

1) subjecting a dicarboxylic acid component comprising terephthalic acid and _{optionally C4-12} aliphatic dicarboxylic acids and isophthalic acid to polycondensation with a _C2-6 diol component, and

2) Add C _16-20 strontium fatty acid to the polycondensation reaction product.

The present invention modifies the polyester diol with C _16-20 fatty acid strontium, so that the synthetic polyester hot melt adhesive has high fluidity, and has good melting stability and bonding strength simultaneously. The high-flow polyester hot-melt adhesive composition has low manufacturing cost and is easy to apply.

Detailed ways

In a preferred embodiment, the polyester diol of the present invention contains 30-100 mole % terephthalic acid, 0-70 mole % isophthalic acid and 0-70 mole % C _4-12 aliphatic binary Carboxylic acid, preferably containing 30-90 mol% terephthalic acid units, 5-45 mol% isophthalic acid units, and 5-45 mol% _C6-10 aliphatic dicarboxylic acid units, the polyester The total number of moles of dicarboxylic acid components in the diol is based on the total number of moles.

In a more preferred embodiment, the polyester diol contains 50 to 80 mole percent terephthalic acid units, 10 to 30 mole percent isophthalic acid units, and 10 to 30 mole percent C _6-10 esters family of dicarboxylic acid units, based on the total moles of dicarboxylic acid components in the polyester diol.

The above-mentioned terephthalic acid, isophthalic acid and C _4-12 aliphatic dicarboxylic acid units can be formed from terephthalic acid, isophthalic acid and C _4-12 aliphatic dicarboxylic acids or their C _{1 -4} alkyl esters are produced.

Examples of _C4-12 aliphatic dicarboxylic acids include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid and dodecanedicarboxylic acid Or their mixtures, preferably succinic acid, adipic acid, suberic acid, sebacic acid or their mixtures, more preferably adipic acid, sebacic acid or their mixtures.

Examples of the above-mentioned C _1-4 alkyl dicarboxylic acid esters include dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate, isophthalic acid Dimethyl formate, Diethyl isophthalate, Dipropyl isophthalate, Dibutyl isophthalate, Dimethyl succinate, Dimethyl glutarate, Dimethyl adipate, Dibutyl adipate, dimethyl pimelate, dibutyl pimelate, dimethyl suberate, dibutyl suberate, dimethyl azelate, dibutyl azelate, decane Dimethyl diacid, dibutyl sebacate, etc. Preferred are dimethyl terephthalate, dimethyl isophthalate, dimethyl adipate, dimethyl sebacate.

The above-mentioned glycol component includes at least one glycol selected from ethylene glycol, propylene glycol, butanediol, pentanediol, and hexylene glycol. The above-mentioned dihydric alcohols may be used alone or in combination of two or more.

In a preferred embodiment, the strontium C _16-20 fatty acid accounts for 0.1 to 5% by weight of the total moles of polyester diol, preferably 0.3 to 2% by weight.

In a more preferred embodiment, the strontium C _16-20 fatty acid is strontium C _16-20 saturated fatty acid, more preferably strontium stearate.

In the polycondensation reaction of dibasic acid component and dibasic alcohol component, can make above-mentioned dibasic acid component and dibasic alcohol component polycondense together under the effect of catalyst, obtain polyester diol of the present invention, However, in order to increase the reaction rate, generally the lower _C1-4 alkyl esters of dibasic carboxylic acids and dibasic alcohols are subjected to transesterification reactions, for example, alkyl terephthalates are first esterified with dibasic alcohols. exchange reaction. The temperature range of the transesterification reaction is generally 100 ~ 250 ° C, preferably 140 ~ 240 ° C. This transesterification reaction may be performed under normal pressure or under reduced pressure. When the effluent reaches 95% of the theoretical value, the esterification reaction ends. Continue to heat up to 240~260°C, and carry out co-condensation reaction under the condition of vacuuming and gradually reducing pressure to obtain polyester hot-melt adhesive. Nitrogen was filled into the reactor, and the vacuum was released to normal pressure. Add C _16-20 strontium fatty acid to the polycondensation product of 1) under stirring, and continue stirring for 10-30 minutes to obtain the polyester hot-melt adhesive composition of the present invention.

In a preferred embodiment, the molar ratio of the above-mentioned dicarboxylic acid or its alkyl ester component to the diol component is preferably 1:(1.1~2), preferably 1:(1.2~1.8), most preferably It is about 1: (1.2~1.6).

The conventional catalysts in the art can be used in the above-mentioned transesterification reaction, such as alkyl titanate, such as tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate.

The amount of the catalyst used in the present invention is about 0.01-0.15% by weight of the total weight of the raw material monomers, preferably 0.01-0.1% by weight.

When the alcohol distilled from the transesterification reaction system reaches the theoretical amount, when the water distilled from the esterification reaction system reaches the theoretical amount, continue to gradually increase the temperature to 240~260°C, and apply about 133Pa The vacuum is used for polycondensation reaction to remove residual water and monomers from the reaction system. In order to prevent the reactants from being discharged from the system, vacuuming should be carried out step by step, gradually changing from low vacuum to high vacuum. The residual pressure of the final system is lower than 133Pa.

Catalysts and stabilizers can be added to the polycondensation reaction system.

The polycondensation catalyst can still use the above-mentioned alkyl titanate, and the addition amount is about 0.01-0.15% by weight, preferably 0.01-0.1% by weight, of the total weight of the polyester hot-melt adhesive.

After the polycondensation reaction was completed, the heating was stopped, and the temperature of the reaction mixture was preferably cooled to below 100° C. under an inert atmosphere such as nitrogen. The strontium _C16-20 fatty acid and optionally other additives such as stabilizers and nucleating agents, antioxidants, colorants, fillers, etc. are then added to the reaction mixture. After uniform stirring, cooling and cutting into pellets, the polyester hot-melt adhesive composition product of the present invention is obtained.

Examples of stabilizers include phosphates and phosphites.

Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate or mixtures thereof.

Examples of phosphites include triphenyl phosphite, triethyl phosphite, tributyl phosphite or mixtures thereof.

The amount of the stabilizer is generally about 0.01-0.1% by weight of the total weight of the raw material monomers, preferably 0.02-0.08% by weight.

Examples of the nucleating agent include one of ultrafine silica, talc and sodium carboxylate, preferably sodium carboxylate.

The amount of nucleating agent is generally 0.01-1.5%, preferably 0.1-1%, of the total weight of the reacted product.

The aforementioned alkyl titanate catalysts can also catalyze esterification and polycondensation reactions.

After the polycondensation reaction, the obtained reaction product was cooled, and the (weight average) molecular weight was measured by gel chromatography (GPC). The weight average molecular weight of the polyester diol of the present invention is generally 10,000-100,000, preferably 20,000-50,000.

For the above polyester diol and its synthesis method, see CN1990810A, for example.

The preparation method of the polyester hot-melt adhesive composition of the present invention can be directly blended in a reaction kettle, and has the advantages of high production efficiency and low production cost.

The polyester hot-melt adhesive composition prepared by the above-mentioned method has low melt viscosity and low specific viscosity decrease rate, and this high-fluidity polyester hot-melt adhesive composition can replace solvent-based adhesives and be directly used in coating process.

Example

The following examples are used to further illustrate the present invention, but it should be understood that these examples cannot be used to limit the protection scope of the present invention. The protection scope of the present invention is defined by the appended claims.

The polyester hot-melt adhesive that makes in each embodiment and comparative example test performance according to the following methods:

Fluidity: evaluated by testing the melt viscosity of polyester, the lower the melt viscosity at the same temperature, the better the fluidity.

Melt heat stability: place the polyester hot melt adhesive in an oven at 230°C for 6 hours, test the value of the specific viscosity after 6 hours, and calculate the decrease rate of the specific viscosity before and after placing, the lower the decrease rate, the better the melt stability the better.

Melt viscosity test method: Accurately weigh 11g polyester hot melt adhesive sample, dry the water in an oven, use Brookfield DV-E type rotational viscometer to test, the test temperature is 230 ℃, the rotor number is S27, and the rotor starts to rotate for 30 minutes. The melt viscosity value displayed on the rear dial and the speed should be adjusted according to the actual situation.

Increased viscosity test: according to the national standard GB/T1632-93, use the Ubbelohde viscometer method to carry out the increased viscosity test to characterize its molecular weight. The solvent used is phenol-tetrachloroethane (the weight ratio is 1:1 ).

Melting point: Mettler's DSC-823c is used to test, after two heating scans, the heating rate is 20°C/min, and the melting peak temperature of the second heating is the melting point.

Example 1

Add 234 grams of 1,4-butanediol in a 1L reactor with a thermometer, a mechanical stirrer, a fractionation column and a condenser, then add 232.4 grams of terephthalic acid and 33.2 grams of isophthalic acid under stirring, 58.4 grams of adipic acid, and 0.23 grams of n-ethyl phthalate. Heat up the temperature. When the temperature rises to about 170°C, water droplets will start to distill. The distillation temperature is 90-100°C. Continue to heat up until the temperature in the kettle reaches about 220°C. When the amount of water distilled reaches the theoretical amount, the esterification is completed and low molecular weight oligomers. Continue to raise the temperature to about 240-250°C, and increase the vacuum of the system until the vacuum of the system is less than 133Pa. When the power of the polycondensation reaction reaches the predetermined value, fill in nitrogen to release the vacuum to normal pressure, add 3.4 grams of strontium stearate (purchased from Shanghai Mingtai Chemical Co., Ltd.), continue stirring for 20 minutes, pour the molten material into cold water while it is hot, and obtain The white glue strip is cut into colloidal particles to obtain the polyester hot-melt adhesive composition of the present invention.

After drying at 100°C for 6 hours, the measured melting point is 176°C, the increased specific viscosity is 0.39, and the melt viscosity is 20800mPa.S/230°C. After the dried polyester hot melt adhesive particles were melted and placed in an oven at 230° C. for 6 hours, the increased specific viscosity was measured to be 0.36.

Examples 2, 3 and 4

The above three embodiments are carried out by the same steps and conditions as in Example 1, except that the raw materials used and their proportioning ratio are shown in Table 1 below. The analytical results of the obtained product are also listed in Table 1.

Comparative example 1

Add 234 grams of 1,4-butanediol in a 1L reactor with a thermometer, a mechanical stirrer, a fractionation column and a condenser, then add 232.4 grams of terephthalic acid and 33.2 grams of isophthalic acid under stirring, 58.4 grams of adipic acid, and 0.23 grams of n-ethyl phthalate. Heat up the temperature. When the temperature rises to about 170°C, water droplets will start to distill. The distillation temperature is 90-100°C. Continue to heat up until the temperature in the kettle reaches about 220°C. When the amount of water distilled reaches the theoretical amount, the esterification is completed and low molecular weight oligomers. Continue to raise the temperature to about 240-250°C, and increase the vacuum of the system until the vacuum of the system is less than 133Pa. When the polycondensation reaction power reaches the predetermined value, fill in nitrogen to release the vacuum to normal pressure, pour the molten material into cold water while it is hot, and obtain white rubber strips, which are cut into colloidal particles.

After drying at 100°C for 6 hours, the measured melting point is 176°C, the increased specific viscosity is 0.39, and the melt viscosity is 31300mPa.S/230°C. After the dried polyester hot-melt adhesive particles were melted and placed in an oven at 230°C for 6 hours, the increased specific viscosity was measured to be 0.34.

Comparative example 2

Comparative Example 2 is carried out according to the steps and methods of Comparative Example 1, the difference is the raw materials and their proportioning, as shown in Table 1 below, and the analysis results of the obtained products are also listed in Table 1.

Comparative Examples 3 and 4

The above two comparative ratios are carried out according to the steps and methods of Example 1, except that the raw materials and proportioning are as shown in Table 1, and the analysis results of the products obtained are also listed in Table 1.

The formula and analysis result of each embodiment of table 1 and comparative example

Note a: the data and effects of Comparative Examples 1, 2, 3, and 4 correspond to Examples 1, 2, 3, and 4 respectively.

In the above table 1, Examples 1, 2, 3, and 4 are examples modified by strontium stearate, Comparative Examples 1 and 2 are examples without modifiers, and Comparative Examples 3 and 4 are modified by modifiers. Examples are calcium stearate and zinc stearate.

As can be clearly seen from the data in the table, after adding strontium stearate to the polyester hot-melt adhesive obtained in Examples 1, 2, 3, and 4 for blending, the melt viscosity of the mixture is obviously reduced, and the flowability is greatly improved; Ratio 1 and 2 do not add strontium stearate and then melt viscosity is obviously higher than embodiment 1 and 2, comparative example 3 and 4 adopt calcium stearate and zinc stearate to modify respectively then reduce melt viscosity effect and be not as good as embodiment 3, 4 Obvious.

It can also be seen from Table 1 that the polyester hot-melt adhesives obtained in Examples 1, 2, 3, and 4, after being melted and placed at 230°C for 6 hours, the rate of decrease in their specific viscosity is less than that of Comparative Examples 1, 2, 3, and 4 respectively. 4 The ratio of viscosity decrease rate of the obtained polyester hot melt adhesive. This illustrates that the polyester hot-melt adhesives obtained in Examples 1, 2, 3, and 4 have better melting thermal stability. It can also be seen from Table 1 that polyester hot-melt adhesives with high melting points (Examples 1 and 3) have better melting thermal stability than polyester hot-melt adhesives with low melting points (Examples 2 and 4).

That is to say, the degradation rate of the polyester hot melt adhesive of the present invention is slower in the molten state, which is obviously more beneficial to melt coating, and there is no need to worry about the hot melt adhesive degrading too fast in the melting tank to affect the coating quality and bonding strength.

Surprisingly, the polyester hot-melt adhesive composition obtained by adding strontium stearate and polyester hot-melt adhesive blending in the reactor not only has better fluidity, but also has Better thermal stability. Adding salts such as calcium stearate and zinc stearate of the same type cannot achieve the same effect.

In addition, the polyester hot-melt adhesive composition of the present invention is obtained by directly blending at high temperature in a reactor without additional blending equipment, and the blending composition has good compatibility and no peculiar smell, so the production efficiency is high and the production cost is low.

Claims (9)

1. a composition of polyester hot-melt adhesive for high workability, it comprises:

A) polyester diol, it is dicarboxylic acid component and C _2-6the polycondensation product of diol component, described dicarboxylic acid component comprises terephthalic acid and non-essential C _4-12aliphatic dicarboxylic acid and m-phthalic acid, its weight-average molecular weight is 10000 ~ 100000, and

B) C _16-20lipid acid strontium, described C _16-20lipid acid strontium accounts for 0.3 ~ 2 % by weight of polyester diol gross weight.

2. composition of polyester hot-melt adhesive as claimed in claim 1, it is characterized in that, in the total mole number of dicarboxylic acid component in described polyester diol, the content of terephthalic acid is 30 ~ 100 % by mole, and the content of m-phthalic acid is 0 ~ 70 % by mole, C _4-12the content of aliphatic dicarboxylic acid is 0 ~ 70 % by mole.

3. composition of polyester hot-melt adhesive as claimed in claim 2, it is characterized in that, in the total mole number of dicarboxylic acid component in described polyester diol, the content of terephthalic acid is 30 ~ 90 % by mole, and the content of m-phthalic acid is 5 ~ 45 % by mole, and C _6-10the content of aliphatic dicarboxylic acid is 5 ~ 45 % by mole.

4. the composition of polyester hot-melt adhesive according to any one of claim 1 ~ 2, is characterized in that, described C _4-12aliphatic dicarboxylic acid selects oneself diacid, suberic acid, sebacic acid and their mixture.

5. composition of polyester hot-melt adhesive as claimed in claim 4, is characterized in that, described C _4-12aliphatic dicarboxylic acid selects oneself diacid, sebacic acid and their mixture.

6. composition of polyester hot-melt adhesive as claimed in claim 1, is characterized in that described C _2-6dibasic alcohol comprises two or more dibasic alcohol be selected from ethylene glycol, propylene glycol, butyleneglycol, hexylene glycol.

7. composition of polyester hot-melt adhesive as claimed in claim 1, is characterized in that, described C _16-20lipid acid strontium is C _16-20saturated fatty acid strontium.

8. composition of polyester hot-melt adhesive as claimed in claim 1, is characterized in that, described C _16-20lipid acid strontium is strontium stearate.

9. the preparation method of the composition of polyester hot-melt adhesive according to any one of claim 1-8, it comprises the steps:

1) make to comprise terephthalic acid and non-essential C _4-12the dicarboxylic acid component of aliphatic dicarboxylic acid and m-phthalic acid and C _2-6diol component carries out polycondensation, and

2) in polycondensation product, C is added _16-20lipid acid strontium.