CN115926699A - A kind of PET bottle labeling hot-melt adhesive and preparation technology thereof - Google Patents

Abstract

The invention relates to the technical field of hot melt adhesives, in particular to the field of IPC 09J7, and more particularly relates to a PET bottle labeling hot melt adhesive and a preparation process thereof. The PET bottle labeling hot melt adhesive comprises the following preparation raw materials in parts by weight: 20-70 parts of thermoplastic elastomer, 30-95 parts of tackifier, 10-35 parts of softener and 0.05-2 parts of anti-aging agent. The prepared PET bottle labeling hot melt adhesive has good initial viscosity, short opening time, no wire drawing, high shear strength, good high and low temperature resistance, no toxicity and no harm, and is particularly suitable for PET bottles such as oil bottles, vinegar bottles, soy sauce bottles and the like.

Description

A kind of hot melt adhesive for PET bottle labeling and its preparation process

Technical Field

The present invention relates to the technical field of hot melt adhesives, in particular to the field of IPC C 09J7, and more specifically to a PET bottle labeling hot melt adhesive and a preparation process thereof.

Background Art

For PET bottle labeling, some companies do not use glue, but directly use self-adhesive labels for labeling. However, the comprehensive performance of self-adhesive labels is poor, and the high and low temperature resistance is not good. Therefore, most companies use water-based glue for labeling, but water-based glue dries slowly and the machine efficiency is low, which seriously affects the output.

In the prior art, a patent application document with application publication number CN1314773A discloses a method for preparing a water-resistant high-speed labeling adhesive by compounding casein and montmorillonite intercalation, and prepares a labeling adhesive with high water resistance and strong resistance to enzyme hydrolysis, but its initial viscosity is not high and its stability at low temperatures is poor.

The patent application document with application publication number CN111471430A discloses a labeling adhesive for glass bottles and a preparation method thereof. The prepared labeling adhesive has a good labeling effect on the surface of the glass bottle, a fast drying time and no drawing, but its performance on PET bottles is average and its shear strength is low.

In recent years, some domestic enterprises have introduced hot melt adhesive labeling equipment, but the effect of labeling hot melt adhesive is generally not good, especially in winter, it is not resistant to low temperatures and is easy to warp, and in summer, it is easy to draw. Therefore, it is necessary to develop a hot melt adhesive with good initial adhesion, short open time, no drawing, high shear strength, and good high and low temperature resistance for PET bottle labeling.

Summary of the invention

In order to solve the above problems, the first aspect of the present invention provides a PET bottle labeling hot melt adhesive. The preparation raw materials include, by weight: 20-70 parts of thermoplastic elastomer, 30-95 parts of tackifier, 10-35 parts of softener, and 0.05-2 parts of antioxidant.

Preferably, the thermoplastic elastomer is one or more of styrene elastomer, silicone elastomer, olefin elastomer, vinyl chloride elastomer, diene elastomer, organic fluorine elastomer, amide elastomer, urethane elastomer, and ethylene elastomer; further preferably, it is a styrene elastomer.

Preferably, the styrene elastomer is one or more of styrene-butadiene-styrene (SBS) block copolymer and styrene-isoprene-styrene (SIS); more preferably, it is SBS block copolymer and SIS block copolymer.

Preferably, the weight ratio of the SBS block copolymer to the SIS block copolymer is 1:(0.5-5); more preferably, it is 1:2.

Preferably, the SBS block copolymer is a hydrogenated SBS block copolymer.

Preferably, the hydrogenated SBS block copolymer has a styrene content of 20-40 wt %, and a viscosity of 500-2000 mPa·s in a 20 wt % toluene solution at 25° C.; further preferably, the hydrogenated SBS block copolymer has a styrene content of 30 wt %, and a viscosity of 1700 mPa·s in a 20 wt % toluene solution at 25° C.

The applicant has found that the use of SBS block copolymers as thermoplastic elastomers can improve the viscosity and high temperature resistance of PET bottle labeling hot melt adhesives. This may be because SBS block copolymers are block copolymers composed of thermoplastic resins and soft elastomers, and have both high elasticity and thermoplastic processability. When used, the cross-linked network structure formed by the hard segment and the soft segment increases the viscosity of the PET bottle labeling hot melt adhesive. However, its viscosity is low, and the unsaturated bonds in its molecular chain make its heat aging resistance poor. The applicant unexpectedly found that the use of hydrogenated SBS block copolymers with a styrene content of 20-40wt% and a viscosity of 500-2000mPa·s in a 20wt% toluene solution at 25°C for the preparation of PET bottle labeling hot melt adhesives can not only improve the high temperature resistance of PET bottle labeling hot melt adhesives, but also improve the initial viscosity of PET bottle labeling hot melt adhesives. This may be due to the hydrogenation reaction that converts the unsaturated bonds in the SBS block copolymer into saturated bonds, thereby improving the stability of the PET bottle labeling hot melt adhesive. On the other hand, a low styrene content will increase the viscosity of the PET bottle labeling hot melt adhesive, but too high a viscosity is not suitable for the PET bottle hot melt adhesive, which will cause the adhesive to draw and take a long time to dry. A high styrene content will cause the PET bottle hot melt adhesive to become brittle, affecting its peel strength. Therefore, a hydrogenated SBS block copolymer with a styrene content of 20-40wt% and a viscosity of 500-2000mPa·s in a 20wt% toluene solution at 25°C is selected. While improving the initial viscosity of the PET bottle labeling hot melt adhesive, it can also improve the curing time and high temperature stability of the PET bottle labeling hot melt adhesive, but the improvement in viscosity is limited and does not have good processing performance.

In some preferred embodiments, the hydrogenated SBS block copolymer may be commercially available, such as YH 502 produced by Hunan Yuehua Chemical Industry Co., Ltd.

Preferably, the SIS block copolymer has a styrene content of 10-30 wt% and a melt index of 5-20 g/10 min; further preferably, the SIS block copolymer has a styrene content of 15 wt% and a melt index of 7-17 g/10 min.

The applicant unexpectedly discovered that the use of SBS block copolymer and SIS block copolymer in a weight ratio of 1: (0.5-5) as thermoplastic elastomers can further improve the viscosity and peel strength of the PET bottle labeling hot melt adhesive. This may be because the SBS block copolymer can combine with the soft segment polyisoprene in the SIS block copolymer to form an elastic network, and the SIS block copolymer has multiple side methyl structures, which can provide strong adhesion for the pressure-sensitive hot melt adhesive, so that the addition of the SIS block copolymer can improve the viscosity of the PET bottle labeling hot melt adhesive. In addition, the use of SIS block copolymers with a styrene content of 10-30wt% and a melt index of 5-20g/10min can improve the processing performance and higher transparency of the PET bottle labeling hot melt adhesive, making it more suitable for use in PET bottle labeling hot melt adhesive. However, SIS block copolymers are expensive and most of them have to be imported, so the cost of use is extremely high. Therefore, the use of SBS block copolymers and SIS block copolymers with a weight ratio of 1: (0.5-5) as thermoplastic elastomers can not only further improve the viscosity and peel strength of the PET bottle labeling hot melt adhesive, but also save costs and have high economic benefits. However, thermoplastic elastomers themselves do not have viscosity, so other ingredients must be added to increase the fluidity of the PET bottle labeling hot melt adhesive and its adhesion to PET bottles and labels.

In some preferred embodiments, the SIS block copolymer may be commercially available, such as YH 1106 produced by Hunan Yuehua Chemical Industry Co., Ltd.

Preferably, the tackifier is one or more of polyterpene resin, hydrocarbon resin, rosin resin, phenolic resin, xylene resin, terpene phenolic resin; more preferably, it is hydrocarbon resin and rosin resin.

Preferably, the weight ratio of the hydrocarbon resin to the rosin resin is 1:(1-5); further preferably, it is 5:7.

Preferably, the hydrocarbon resin is one or more of aliphatic hydrocarbon resin (C5), alicyclic hydrocarbon resin (DCPD), aromatic hydrocarbon resin (C9), aliphatic/aromatic copolymer hydrocarbon resin (C5/C9), C5 hydrogenated hydrocarbon resin, and C9 hydrogenated hydrocarbon resin; further preferred is C5 hydrogenated hydrocarbon resin.

Preferably, the softening point of the C5 hydrogenated hydrocarbon resin is 90-110° C., and the melt viscosity at 200° C. is 150-250 cps; further preferably, the softening point of the C5 hydrogenated hydrocarbon resin is 97-104° C., and the melt viscosity is 190-200 cps.

In some preferred embodiments, the C5 hydrogenated hydrocarbon resin may be commercially available, such as LH-1100 produced by Shandong Luhua Energy Group Co., Ltd.

Preferably, the rosin resin is one or more of maleated rosin resin, hydrogenated rosin resin, polymerized rosin resin, and disproportionated rosin resin; more preferably, it is hydrogenated rosin resin.

Preferably, the softening point of the hydrogenated rosin resin is 80-100° C., and the acid value is 3-15 mgKOH/g; further preferably, the softening point of the hydrogenated rosin resin is 82-88° C., and the acid value is 5-10 mgKOH/g.

In some preferred embodiments, the hydrogenated rosin resin may be commercially available, such as GA-85H produced by Arakawa Corporation of Japan.

The applicant unexpectedly discovered that the use of aliphatic hydrocarbon resin and rosin resin in a weight ratio of 1: (1-5) can improve the stability and adhesion of the PET bottle labeling hot melt adhesive. This may be because the aliphatic hydrocarbon resin has excellent compatibility with both SIS block copolymers and SBS block copolymers, which can improve the wettability of the PET bottle labeling hot melt adhesive to the substrate, allowing the two to fully contact and thus improve adhesion. However, since the unsaturated bonds in the hydrocarbon resin will affect the weather resistance of the PET bottle labeling hot melt adhesive, and the colloid color is dark, it is not suitable for use in PET bottle labeling PET bottle labeling hot melt adhesive. The applicant unexpectedly discovered that the use of hydrogenated aliphatic hydrocarbon resin with a softening point of 90-110°C and a melt viscosity of 150-250cps at 200°C can not only improve the adhesion of the PET bottle labeling hot melt adhesive, but also the color of the hydrogenated aliphatic hydrocarbon resin becomes lighter, making it suitable for use in PET bottle labeling hot melt adhesive. In addition, the higher softening point also allows it to exist in the system in an aggregated form, which increases the cohesive force and prevents the PET bottle labeling hot melt adhesive from drawing. However, a single-component tackifier has limited effect on the adhesion of the PET bottle labeling hot melt adhesive. The applicant unexpectedly discovered that when a hydrogenated rosin resin with a softening point of 80-100°C and an acid value of 3-15 mgKOH/g is added, and the mass ratio of hydrogenated aliphatic hydrocarbon resin to hydrogenated rosin resin is 1: (1-5), the two can work synergistically, which can not only improve the initial adhesion and peel strength of the PET bottle labeling hot melt adhesive based on SBS block copolymers and SIS block copolymers, meet the needs of PET bottle labeling hot melt adhesive, but also the rosin resin is cheap, which can improve the economic benefits of PET bottle labeling hot melt adhesive.

Preferably, the softener is one or more of phthalates, white oil, liquid paraffin, cyclohexane oil, polyethylene glycol, and fatty acid esters; more preferably, it is cyclohexane oil.

Preferably, the kinematic viscosity of the naphthenic oil at 40° C. is 150-160 mm ² /s; more preferably, it is 158.1 mm ² /s.

The applicant unexpectedly discovered that adding a certain amount of cyclopentane oil as a softener can improve the initial adhesion and peel strength of the hot melt adhesive for PET bottle labeling. This may be because cyclopentane oil contains non-polar small molecules such as cyclohexane, which can be inserted into the isoprene molecular chain segment in the thermoplastic elastomer to increase the distance between molecules and weaken the interaction between the soft segments, thereby increasing the softness of the thermoplastic elastomer, improving the ability of the PET bottle labeling hot melt adhesive to wet the surface of the PET bottle, and then improving the peel strength and initial adhesion of the PET bottle labeling hot melt adhesive. However, if the amount added is too much, some non-polar small molecules will be inserted into the hard segment, affecting the cross-linking effect between the polar groups on the hard segment molecular chain, which will sharply reduce the peel strength and initial adhesion of the PET bottle labeling hot melt adhesive. The applicant has found that when the weight of the softener is 10-35% of the total weight of the PET bottle labeling hot melt adhesive, not only can the initial adhesion and peel strength of the PET bottle labeling hot melt adhesive be improved, but also the naphthenic oil is non-toxic and harmless, and is suitable for use in PET bottle labeling hot melt adhesives such as oil bottles, vinegar bottles, and soy sauce bottles.

In some preferred embodiments, the softener may be commercially available, such as KN4010 produced by Guangdong Zhonghai Nanlian Energy Co., Ltd.

Preferably, the weight of the softener is 10-35% of the total weight of the PET bottle labeling hot melt adhesive; more preferably, it is 20%.

Preferably, the antioxidant is N-cyclohexyl-N'-phenyl-p-phenylenediamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2-oxalyl-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)] propionate, 1,3,5-tris( One or more of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, tris(2,4-di-tert-butylphenyl) phosphite, and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate; further preferred are β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate.

Preferably, the weight ratio of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate to bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate is 1:(0.5-3); more preferably, it is 1:1.5.

1076。In some preferred embodiments, the β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester can be commercially available, such as the one produced by Tianjin Lianlong New Materials Co., Ltd.

1076.

626。In some preferred embodiments, the bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate can be commercially available, such as the one produced by Tianjin Lianlong New Materials Co., Ltd.

626.

A second aspect of the present invention provides a method for preparing the above-mentioned hot melt adhesive for labeling PET bottles, comprising the following steps:

After mixing the thermoplastic elastomer, add the tackifier, softener and antioxidant, heat to 100-130°C and introduce nitrogen protection until the mixture is basically melted, then raise the temperature to 135-160°C, and stir until the solution is uniform and transparent.

Beneficial effects:

1. By selecting a hydrogenated SBS block copolymer with a styrene content of 20-40wt% and a viscosity of 500-2000mPa·s in a 20wt% toluene solution at 25°C, the initial viscosity of the PET bottle labeling hot melt adhesive can be improved while also improving the curing time and high temperature stability of the PET bottle labeling hot melt adhesive, and it is not easy to draw.

2. By selecting a SIS block copolymer with a styrene content of 10-30wt% and a melt index of 5-20g/10min, the processing performance and higher transparency of the PET bottle labeling hot melt adhesive can be improved, making it more suitable for use in the PET bottle labeling hot melt adhesive.

3. By selecting SBS block copolymer and SIS block copolymer with a weight ratio of 1: (0.5-5) as thermoplastic elastomer, not only can the viscosity and peel strength of the PET bottle labeling hot melt adhesive be further improved, but also the cost can be saved, which has high economic benefits.

4. By selecting a hydrogenated aliphatic hydrocarbon resin with a softening point of 90-110°C and a melt viscosity of 150-250cps at 200°C, not only can the adhesion of the PET bottle labeling hot melt adhesive be improved, but the hydrogenated aliphatic hydrocarbon resin also becomes lighter in color, making it suitable for use in PET bottle labeling hot melt adhesive and not prone to drawing.

5. By adding hydrogenated rosin resin with a softening point of 80-100°C and an acid value of 3-15 mgKOH/g, and the mass ratio of hydrogenated aliphatic hydrocarbon resin to hydrogenated rosin resin is 1:(1-5), not only the initial adhesion and peel strength of the PET bottle labeling hot melt adhesive based on SBS block copolymer and SIS block copolymer can be improved to meet the needs of PET bottle labeling hot melt adhesive, but also the rosin resin is cheap, which can improve the economic benefits of PET bottle labeling hot melt adhesive.

6. By selecting 10-35% of the total weight of the PET bottle labeling hot melt adhesive as a softener, not only can the initial adhesion and peel strength of the PET bottle labeling hot melt adhesive be improved, but the cyclopentane oil is also non-toxic and harmless, and is suitable for use in PET bottle labeling hot melt adhesives such as oil bottles, vinegar bottles, and soy sauce bottles.

7. The PET bottle labeling hot melt adhesive prepared by the present invention is not only suitable for PET bottles, such as oil bottles, soybean oil bottles, vinegar bottles, soy sauce bottles, etc., but also suitable for sealing, paper product processing, flexible packaging, envelopes, textiles, cigarette glue, non-woven fabrics and other fields.

DETAILED DESCRIPTION

Example

Example 1

Example 1 provides a PET bottle labeling hot melt adhesive. The raw materials for preparation include, by weight: 45 parts of thermoplastic elastomer, 60 parts of tackifier, 26.5 parts of softener, and 1 part of antioxidant.

The thermoplastic elastomer is a styrene elastomer.

The styrene elastomer is SBS block copolymer and SIS block copolymer.

The weight ratio of the SBS block copolymer to the SIS block copolymer is 1:2.

The SBS block copolymer is a hydrogenated SBS block copolymer.

The hydrogenated SBS block copolymer has a styrene content of 30 wt % and a viscosity of 1700 mPa·s in a 20 wt % toluene solution at 25° C.

The hydrogenated SBS block copolymer was purchased from a supplier, YH502 produced by Hunan Yuehua Chemical Industry Co., Ltd.

The SIS block copolymer has a styrene content of 15 wt % and a melt index of 7-17 g/10 min.

The SIS block copolymer was purchased from a supplier, Hunan Yuehua Chemical Industry Co., Ltd., and produced YH 1106.

The tackifiers are hydrocarbon resin and rosin resin.

The weight ratio of the hydrocarbon resin to the rosin resin is 5:7.

The hydrocarbon resin is C5 hydrogenated hydrocarbon resin.

The softening point of the C5 hydrogenated hydrocarbon resin is 97-104° C., and the melt viscosity is 190-200 cps.

The C5 hydrogenated hydrocarbon resin was purchased from a supplier, Shandong Luhua Energy Group Co., Ltd., and was produced by the manufacturer, LH-1100.

The rosin resin is hydrogenated rosin resin.

The softening point of the hydrogenated rosin resin is 82-88° C., and the acid value is 5-10 mgKOH/g.

The hydrogenated rosin resin was purchased from a supplier, GA-85H produced by Arakawa Corporation of Japan.

The softener is naphthenic oil.

The kinematic viscosity of the naphthenic oil at 40° C. was 158.1 mm ² /s.

The softener was purchased from a supplier, Guangdong Zhonghai Nanlian Energy Co., Ltd., and was produced as KN4010.

The antioxidants are β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate.

The weight ratio of the β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester to bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate is 1:1.5.

1076。The β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate was purchased from Tianjin Lianlong New Materials Co., Ltd.

1076.

626。The bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate was purchased from Tianjin Lianlong New Materials Co., Ltd.

626.

A second aspect of the present invention provides a method for preparing the above-mentioned hot melt adhesive for labeling PET bottles, comprising the following steps:

After mixing the thermoplastic elastomer, add the tackifier, softener and antioxidant, heat to 110°C and introduce nitrogen protection until the mixture melts, then raise the temperature to 150°C and stir until the solution is uniform and transparent.

Example 2

Example 2 provides a hot melt adhesive for labeling PET bottles. The specific implementation method is the same as that of Example 1, except that: in parts by weight, the preparation raw materials include: 30 parts of thermoplastic elastomer, 30 parts of tackifier, 10 parts of softener, and 0.05 parts of antioxidant.

The weight ratio of the SBS block copolymer to the SIS block copolymer is 2:1.

The weight ratio of the hydrocarbon resin to the rosin resin is 1:1.

The weight ratio of the β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester to bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate is 2:1.

Example 3

Example 3 provides a hot melt adhesive for labeling PET bottles. The specific implementation method is the same as that of Example 1, except that: in parts by weight, the preparation raw materials include: 60 parts of thermoplastic elastomer, 45 parts of tackifier, 20 parts of softener, and 0.5 parts of antioxidant.

The weight ratio of the SBS block copolymer to the SIS block copolymer is 1:5.

The weight ratio of the hydrocarbon resin to the rosin resin is 1:3.

The weight ratio of the β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester to bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate is 2:1.

Example 4

Example 4 provides a hot melt adhesive for labeling PET bottles. The specific implementation method is the same as that of Example 1, except that the weight ratio of the hydrocarbon resin to the rosin resin is 2:1.

Example 5

Example 5 provides a PET bottle labeling hot melt adhesive, and the specific implementation method is the same as that of Example 1, except that: the weight portion of the softener is 70 parts (approximately 40% of the total weight of the PET bottle labeling hot melt adhesive).

Performance Testing Methods

1. Peel strength

The PET bottle labeling hot melt adhesive prepared in Examples 1-5 was applied to a layer of PET, and another layer of PET was covered thereon. After standing for 24 hours, the peel strength was measured using the national standard GB/T 2792-2014, and the results were recorded in Table 1.

2. Initial viscosity

The initial tack of the PET bottle labeling hot melt adhesives prepared in Examples 1-5 was tested with reference to GB/T31125-2014, and the results are recorded in Table 1.

3. Weather resistance

Low temperature resistance:

The PET bottle labeling hot melt adhesive prepared in Examples 1-5 was coated on label paper, and then attached to the surface of the PET oil bottle. After being placed for 24 hours until it was completely attached, it was placed in an environment of -10°C for 24 hours, taken out, and the paper label was torn off to observe whether the paper label can be torn off smoothly. If the label cannot be torn off smoothly, it means that the label is broken. The broken material indicates that the peel strength between the labeling adhesive and the surface of the oil bottle is high and the low-temperature stability is good. The results are recorded in Table 1.

High temperature resistance:

The PET bottle labeling hot melt adhesive prepared in Examples 1-5 was coated on label paper, and then attached to the surface of the PET oil bottle. After being placed for 24 hours until it was completely attached, it was placed in an environment of 70°C for 24 hours, taken out, and the paper label was torn off to observe whether the paper label can be torn off smoothly. If the label cannot be torn off smoothly, it means that the label is broken. The broken material indicates that the peel strength between the labeling adhesive and the surface of the oil bottle is high and the high temperature stability is good. The results are recorded in Table 1.

4. Opening hours

The open time of the PET bottle labeling hot melt adhesives prepared in Examples 1-5 was measured using HG/T 3716-2003, and the results are recorded in Table 1.

Table 1

Claims (10)

1. A hot melt adhesive for labeling PET bottles, characterized in that, in parts by weight, its preparation raw materials include: 20-70 parts of thermoplastic elastomer, 30-95 parts of tackifier, 10-35 parts of softener, and 0.05-2 parts of antioxidant. 2. A PET bottle labeling hot melt adhesive according to claim 1, characterized in that the thermoplastic elastomer is one or more of styrene elastomer, silicone elastomer, olefin elastomer, vinyl chloride elastomer, diene elastomer, organic fluorine elastomer, amide elastomer, urethane elastomer, and ethylene elastomer. 3. The PET bottle labeling hot melt adhesive according to claim 2, characterized in that the thermoplastic elastomer is a styrene elastomer. 4. A PET bottle labeling hot melt adhesive according to any one of claims 1 to 3, characterized in that the tackifier is one or more of polyterpene resin, hydrocarbon resin, rosin resin, phenolic resin, xylene resin, and terpene phenolic resin. 5. A PET bottle labeling hot melt adhesive according to claim 4, characterized in that the tackifier is hydrocarbon resin and rosin resin. 6. A PET bottle labeling hot melt adhesive according to claim 5, characterized in that the weight ratio of the hydrocarbon resin to the rosin resin is 1:(1-5). 7. The hot melt adhesive for labeling PET bottles according to claim 3, characterized in that the styrene elastomer is an SBS block copolymer and a SIS block copolymer. 8. The hot melt adhesive for labeling PET bottles according to claim 7, characterized in that the weight ratio of the SBS block copolymer to the SIS block copolymer is 1:(0.5-5). 9. A PET bottle labeling hot melt adhesive according to any one of claims 1 to 8, characterized in that the antioxidant is N-cyclohexyl-N'-phenyl-p-phenylenediamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene , 2,2-oxalyl-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, tris(2,4-di-tert-butylphenyl) phosphite, and one or more of bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate. 10. A process for preparing a hot melt adhesive for labeling PET bottles according to any one of claims 1 to 9, characterized in that it comprises the following steps: After mixing the thermoplastic elastomer, add the tackifier, softener and antioxidant, heat to 100-130°C and introduce nitrogen protection until the mixture is basically melted, then heat to 135-160°C, and stir until the solution is uniform and transparent.